By VICTOR NZE
United States-based aircraft manufacturer, Boeing has issued a warning to operators of its 737 Max series aircraft following the recent crash of a Lion Air plane in Indonesia that killed all 189 passengers including crew.
The warning by Boeing which came in the wake of the crash follows another one by Indonesian investigators which suggests that the pilots on the ill-fated Lion Air 737 Max 8 were battling the plane as its computers commanded a steep dive during its final moments of flight.
Outside North America, Lion Air is the biggest customer of the Boeing 737 Max, while Air Peace in Nigeria is soon to become the aircraft’s largest operator in Africa with 10 aircraft.
Other operators include: Southwest Airlines 23; Air Canada 18; American Airlines 15; Norwegian Air Shuttle 12; Air China 11; Air Lease 11; China Eastern Airlines 11; China Southern Airlines 11; GE Capital Aviation Services 8; WestJet Airlines 8; Xiamen Airlines 8.
It would be recalled that on October 29, a Boeing 737 Max 8 aircraft crashed in the sea shortly after takeoff, killing all 189 people on board.
Data extracted from the flight recorders revealed that the aircraft experienced problems with airspeed indicators during its last four flights.
In its bulletin issued, Wednesday, Boeing cautioned that the so-called angle-of-attack sensor can provide false readings in limited circumstances, such as when a plane’s autopilot is switched off, that cause the 737 Max to pitch nose downward. The sensor malfunction can essentially trick the plane into pointing its nose down to gain the speed it thinks it needs to keep flying.
Although the Boeing directive does not call for operators to conduct new inspections or take other action, it merely stressed that pilots should follow procedures in the flight manual when encountering erroneous data.
These warnings are also similar to the one issued by United States regulator, Federal Aviation Administration, according to an emailed statement which told operators, last Wednesday, to follow Boeing’s instructions and add information to pilot manuals showing how to diagnose the problem and respond.
The FAA said the problem “could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain.”
On its part, the Indonesia National Transportation Safety Committee in its statement disclosed, Wednesday, that the sensor on the ill-fated Lion Air jet was replaced the day before after it failed on a previous trip, adding that the malfunction can cause the plane’s computers to erroneously detect a mid-flight stall in airflow, causing the aircraft to abruptly dive to regain the speed it needs to keep flying.
On a previous flight from Bali to Jakarta, the angle-of-attack sensor feeding the captain’s flight displays registered a 20-degree difference from the device on the copilot’s side of the cockpit, the committee said. Pilots on that flight were able to compensate.
An angle-of-attack sensor that had been removed before that previous flight has been brought to the investigators and will be examined in the U.S., the Indonesian officials said.
It is still possible the FAA may order Boeing to redesign the equipment or software as investigators piece together details of the Oct. 29 crash, which killed 189 people. The agency said it “will take further appropriate actions depending on the results of the investigation.”
The new information about Lion Air Flight 610 raises multiple questions investigators will want to examine on the pilots’ actions, how flight crews were trained and whether the maintenance performed on the system was adequate, said Roger Cox, a former NTSB investigator.
“I would definitely be looking at the man-machine interface and how pilots respond,” said Cox, a former airline pilot who flew earlier versions of the 737 and specialized at the NTSB in cockpit actions.
One of the puzzling things about the accident is that the plane was flying in clear skies during daylight, so pilots should have been able to handle the problems they faced with airspeed and erroneous sensors, Cox said. However, in rare instances, accidents have been caused by what investigators call a “startle factor.”
“If you don’t take the appropriate action because you’re surprised, you can make a serious error,” he said.
The Lion Air jetliner plunged into the Java Sea minutes after takeoff from Jakarta airport, nosing downward so suddenly that it may have hit speeds of 600 miles an hour before slamming into the water.
Moments earlier, the pilots radioed a request to return to Jakarta, but never turned back toward the airport, according to Indonesia’s safety commission and flight-tracking data. The agency said the pilots were dealing with an erroneous airspeed indication.
Boeing, which is headquartered in Chicago, said it is cooperating fully and providing technical assistance as the investigation continues.
While modern jetliners primarily operate on autopilot, the computerized system can disengage when airspeed indicators malfunction, forcing pilots to manually fly the aircraft. If there is an “uncommanded nose-down stabilizer trim” on the Max, pilots can counteract it by pushing a switch on their control yoke. But the plane’s computers will resume trying to dive as soon as they release the switch, the Boeing bulletin said.
According to the bulletin, flight crews should follow a separate protocol to halt the plane’s potentially dangerous action, according to the bulletin. Pilots are supposed to memorize a procedure to disengage the angle-of-attack inputs to the plane’s computer system.
Till date, Boeing has delivered 219 Max planes, the latest and most advanced 737 jets, since the models made their commercial debut last year with a Lion Air subsidiary.
“The angle-of-attack sensor is intended to measure the angle between air flow and a reference line on the frame or wings so that they maintain lift. If the flow is disrupted by a plane going too slow or climbing too steeply, that can cause an aerodynamic stall and a plane will plummet. However, if the sensor malfunctions, it can cause the plane’s computers to erroneously think it is in a stall, which can then command the aircraft to abruptly dive,” the bulletin stated.
Pilots raise and lower the nose of Boeing jetliners by pushing and pulling on a yoke in the cockpit, which controls panels at the tail known as elevators. In addition, a system known as pitch trim can be changed to prompt nose-up or nose-down movement.
The angle of attack readings are fed into a computer that in some cases will attempt to push down the nose using the pitch trim system. In the early days of the jet age, the pitch trim system was linked to several accidents. If pilots are not careful, they can cause severe nose-down trim settings that make it impossible to level a plane.
The 737 MAX is Boeing’s newest and most advanced aircraft series, as well as the company’s bestseller. The jets have been in high demand and enjoyed a good reputation as safe and reliable carriers.
However, last year Boeing had to briefly ground its 737 Max fleet as discrepancies were found in its engines. Later, several jets were grounded by India’s Jet Airways, also due to engine problems.
The ill-fated Lion Air Boeing 737-Max 8 plane plunged into the Java Sea minutes after take-off from Jakarta to Pangkal Pinang city.
All 189 people on board were killed and the Indonesian National Transportation Safety Committee has said that flight recorder data has so far revealed the plane’s air speed indicator had not been working properly on its last four journeys, including on the fatal flight.
However, the preliminary result of the investigation will only be known at the end of November.
Only the indigenous carrier, Air Peace has the embattled B737 Max in its fleet, which it intends to deploy to newly-designated international routes.
Air Peace has said it intends to bridge the gap created by the country’s inability to exploit the numerous air service agreements it signed with other countries when the carrier fully deploys its newly-acquired fleet of four B777 aircraft as well as the B737-Max.
The airline’s chairman, Allen Onyema disclosed this last month when he stated that its orders, the Boeing 737Max will be deployed to service routes including Paris, Frankfurt, Amsterdam, Sharjah, Jeddah from Abuja, Dubai from Kano as well as London from Enugu among others.
”On the international scene, why did we buy four 777? Why did we order 10 brand new 737Max? You know the max has over 7000 nautical miles range. We brought all these equipment because we want to cover that gap that is making the government of the day worried and for people of this country.
“Those 737Max, we don’t want Nigerians to fly through London to get to Amsterdam. We don’t want Nigerians to pay through their noses to get to their destinations Air Peace decided to bring these jets, the state-of -the-art Boeing 777 and brand new 737Max in other to do these destinations direct for Nigerians.
“We want to start flying Lagos to Paris direct with those max, we want to deploy another max from Lagos to Frankfurt. We want to deploy the Max from Lagos to Amsterdam. We want to deploy it to Milan, we want to deploy it from Abuja to Jeddah. We want to do Kano to Dubai, we want to do Enugu-London with it and some days we use our triple seven to London through Lagos where majority of people travel.
“So the triple sevens are made for the London route, US route because of its range, meant for China because of its range too and cargo. It is meant in some days to go to Johannesburg because of the traffic there too. Most of the work like Mumbai and others will be done by the 737Max which will take like 180 passengers.
“You are not going to go to Mumbai with full load of three hundred and seventy something that the 777 will carry so we decided to do that route with the 737Max. So what are we looking for again? An airline has emerged from this country to plug the gaps,” he said.